Skewness in Box Plots

How to Identify Skewness in Box Plots

By Rob Moore

A box plot is a type of plot that displays the five-number summary of a dataset, which includes:

• The Minimum Value

• The first quartile (the 25th percentile)

• The median value

• The third quartile (the 75th percentile)

• The maximum value
  
  

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Box Plot

We can determine whether or not a distribution is skewed based on the location of the median value in the box plot.

Skewness: Measures the asymmetry of a data set

When the median is closer to the bottom (left) of the box and the whisker is shorter on the lower end of the box, the distribution is right-skewed (or “positively” skewed).

Right-Skewed

When the median is closer to the top (right)of the box and the whisker is shorter on the upper end of the box, the distribution is left-skewed (or “negatively” skewed).

Left-Skewed

When the median is in the middle of the box and the whiskers are roughly equal on each side, the distribution is symmetrical (or “no” skew).

No-Skew

Categorize

Options (12)

Organize these Box and Whisker Plots and their descriptions into the correct category.

Right "positively" Skewed

Left "negatively" Skewed

No-Skew "symmetrical